Typically a screed is a plank or board that is raked over rails or flat supports at both edges to flatten wet concrete to a planar surface at the same height as the top edge of the support rails. However, in a second application of this invention, a screed is used by bricklayers or construction crews in preparing a flat surface of dry bedding mix such as sand or sand/concrete prior to laying brick or paving blocks for walkways, patios or the like. A carefully laid edge of bricks or paving blocks, known as a soldier's course, is first laid around the perimeter of the area to be covered and allowed to set. The top surface of this soldier's course defines a plane. The filler blocks or bricks must be laid so that their top surfaces are properly co-planar with the soldier's course. This necessitates excavating the enclosed ground area below the edge brick height and then introducing a layer of bedding mix so that the blocks or bricks laid in the central area have their bottom surface exactly a brick or block height below the top surface of the bricks or blocks of the soldier's course. A board or plank with bottom corners cut out at the height of a brick/block is commonly used as a screed to flatten the inside surface; it is sized so that the bottom length is slightly less than the width of the inside of the soldier's course. Then, this screed is passed over the tops of the soldier's course bricks/blocks. This involves careful cutting of the board, especially the height dimension of the bottom corner cut-outs.
The prior art relates to screeds and screed supports or rails. U.S. Pat. No. 2,373,284 of Autrey describes an adjustable screed using multiple adjustable legs and wire tie downs to maintain a proper grade elevation while rodding or leveling fresh concrete. It is not useful for laying brick/block for paving. U.S. Pat. No. 5,154,536 of Ciudaj describes an adjustable screed rail that is height adjustable and lockable via bolts and wing nuts in slotted holes in web sections of two mating parts of the rail. U.S. Pat. No. 4,945,698 of Jertberg et al. describes an adjustable screed support for use on walls; this also is a two-part rail type system with adjustment from bolts and nuts in slotted holes. Since the paving application relies on the top surface of the soldier's course for plane determination, there is not a use for adjustable rails or supports such as Ciudaj '536 or Jertberg '698. Another distinction is that the latter two patents describe elements for one-time use which are embedded in the concrete structure. Other prior art, such as U.S. Pat. Nos. 5,460,461 of McGrath, U.S. Pat. No. 5,324,085 of Hintz, and Des. 483,632 of Masseria, relates to handles attached to screed boards. These are not height adjustable screeds.
A commercial height adjustable screed of Pave Tech Corporation includes a rail oriented system using rollers on the bricks of the course as a rail. The screed is a metal scoop. The Pave Tech device is not a set of L-shaped brackets retrofitted to a common board. Instead, it uses a specialized screed shovel scoop requiring an upward bar, and a complicated roller mechanism as part of the adjustment feature.